Ex Situ Left Ventricular Pressure-Volume Loop Analyses for Donor Hearts: Proof of Concept in an Ovine Experimental Model.

Ex situ heart perfusion (ESHP) has emerged as an important strategy to preserve donation after brain death (DBD) and donation after circulatory death (DCD) donor hearts. Clinically, both DBD and DCD hearts are successfully preserved using ESHP. Viability assessment is currently based on biochemical values, while a reliable method for graft function assessment in a physiologic working mode is unavailable. As functional assessment during ESHP has demonstrated the highest predictive value of outcome post-transplantation, this is an important area for improvement. In this study, a novel method for ex situ assessment of left ventricular function with pressure-volume loop analyses is evaluated. Ovine hearts were functionally evaluated during normothermic ESHP with the novel pressure-volume loop system. This system provides an afterload and adjustable preload to the left ventricle. By increasing the preload and measuring end-systolic elastance, the system could successfully assess the left ventricular function. End-systolic elastance at 60 min and 120 min was 2.8 ± 1.8 mmHg/mL and 2.7 ± 0.7 mmHg/mL, respectively. In this study we show a novel method for functional graft assessment with ex situ pressure-loop analyses during ESHP. When further validated, this method for pressure-volume assessments, could be used for better graft selection in both DBD and DCD donor hearts.

Dilemmas concerning heart procurement in controlled donation after circulatory death.

With an expanding population at risk for heart failure and the resulting increase in patients admitted to the waiting list for heart transplantation, the demand of viable organs exceeds the supply of suitable donor hearts. Use of hearts after circulatory death has reduced this deficit. Two primary techniques for heart procurement in circulatory death donors have been described: direct procurement and perfusion and thoraco-abdominal normothermic regional perfusion. While the former has been accepted as an option for heart procurement in circulatory death donors, the latter technique has raised some ethical questions in relation to the dead donor rule. In this paper we discuss the current dilemmas regarding these heart procurement protocols in circulatory death donors.

Curriculum structure: principles and strategy.

This report provides general guidelines for the structure of a curriculum, followed by specific advice on the principles of learning and teaching, the process of restructuring and change leadership and management. It provides examples of several educational philosophies, including vertical and horizontal integration. It discusses the use of competence, learning outcomes, level of degree and assessment and provides a number of recommendations. It does not seek to be prescriptive of time allocation to disciplines within a curriculum. Although this report has been written primarily for those who will develop an undergraduate curriculum, the information may be sufficiently generic to apply to the recent development in graduate entry ('shortened dental' or 'accelerated') courses and to postgraduate degree planning and higher education certificate or diploma courses for other dental care professionals (auxiliaries). The report may have a European bias as progress is made to converge and enhance educational standards in 29 countries with different educational approaches - a microcosm of global collaboration.

Milk urea nitrogen as a tool to monitor the protein nutrition of dairy cows.

The relationship between protein nutrition and milk urea N was investigated in three experiments with a total of 125 cows. After 4 wk of pretreatment, cows received 1 of 13 diets with different ratios of protein to energy for 16 wk. Milk was sampled individually for urea analyses during pretreatment and during wk 1, 5, 10, and 15 of treatment. Results were compared with N losses estimated from rumen fermentation and with N losses of metabolic origin. The mean milk urea N concentration was 12.6 mg/100 ml of milk (range, 9.0 to 18.3 mg). For bulk samples especially, the rumen efflux of crude protein intake was the main determinant of the variation in milk urea N (r2 = 0.81; residual SD = 1.1). However, N losses from the rumen explained only about 50% of the variation in the milk urea N content of samples from individual cows. The N losses of metabolic origin, which, in these experiments, were responsible for 47 to 100% of urinary N losses, were not related to milk urea N. Results showed that regular measurement of milk urea N in bulk samples can be used to monitor N losses from rumen fermentation. However, the value does not give an indication of the efficiency with which the absorbed protein is utilized.